High load capacity hybrid foil bearing

ABSTRACT

A bearing includes a bearing sleeve with a first portion and a second portion adjacent to the first portion. A bump foil extends along an inner face of the first portion of the bearing sleeve and a metal mesh extends along an inner face of the second portion of the bearing sleeve. A top foil extends along an inner face of the bump foil of the first portion and the metal mesh of the second portion.

BACKGROUND

The present invention relates to a bearing, and in particular, to ahybrid foil bearing.

Air cycle machines are used in environmental control systems in aircraftto condition air for delivery to an aircraft cabin. Conditioned air isair at a temperature, pressure, and humidity desirable for aircraftpassenger comfort and safety. At or near ground level, the ambient airtemperature and/or humidity is often sufficiently high that the air mustbe cooled as part of the conditioning process before being delivered tothe aircraft cabin. At flight altitude, ambient air is often far coolerthan desired, but at such a low pressure that it must be compressed toan acceptable pressure as part of the conditioning process. Compressingambient air at flight altitude heats the resulting pressured airsufficiently that it must be cooled, even if the ambient air temperatureis very low. Thus, under most conditions, heat must be removed from airby the air cycle machine before the air is delivered to the aircraftcabin. A cabin air compressor can be used to compress air for use in anenvironmental control system. The cabin air compressor includes a motorto drive a compressor section that in turn compresses air flowingthrough the cabin air compressor.

Both air cycle machines and cabin air compressors have a shaft extendingdown a central axis that rotates. Bearings are positioned outward fromthe shaft to reduce friction between the rotating shaft and stationarycomponents. Historically, ball bearings were used in air cycle machinesand cabin air compressors. Ball bearings face limitations in that theywear out quickly and thus need to be replaced often. Further, ballbearings require oil for operation and the smell of the oil can seepinto the air flowing through the air cycle machine and/or cabin aircompressor before the air is delivered to the aircraft cabin.

To overcome the limitations of ball bearings, air bearings were laterdeveloped for use in air cycle machines and cabin air compressors. Airbearings create an air gap between a rotating part and the bearingcomponents so that the air gap acts as the bearing. Examples of airbearings that can be used are bump foil bearings and metal meshbearings. Bump foil bearings include a bump foil positioned between atop foil and a bearing sleeve. Metal mesh bearings include a metal meshpositioned between a top foil and a bearing sleeve. With both bump foilbearings and metal mesh bearings the top foil is positioned around theshaft. As air flows along the shaft, the top foil is pushed outward fromthe shaft to create an air gap between the rotating shaft and the topfoil. Bump foil bearings have a high stiffness and can support highloads but have low dampening characteristics. The low dampeningcharacteristics can lead to a phenomenon known as sub-synchronous whirl,which is the problem of uncontrolled vibration of the shaft. Metal meshbearings have high dampening characteristics, but sag over time causingthe shaft to become off centered.

SUMMARY

A bearing includes a bearing sleeve with a first portion and a secondportion adjacent to the first portion. A bump foil extends along aninner face of the first portion of the bearing sleeve and a metal meshextends along an inner face of the second portion of the bearing sleeve.A top foil extends along an inner face of the bump foil of the firstportion and the metal mesh of the second portion.

A rotary machine includes a shaft that is configured to rotate in therotary machine, a stationary component positioned outward from theshaft, and a hybrid foil bearing positioned between the shaft and thestationary component. The hybrid foil bearing has a first bump foilportion and a first metal mesh portion adjacent to the first bump foilportion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an air cycle machine.

FIG. 2 is a cross-sectional view of an air compressor.

FIG. 3 is a cross-sectional view of a first embodiment of a hybrid foilbearing.

FIG. 4 is a cross-sectional view of a metal mesh section of the hybridfoil bearing taken along line 4-4 of FIG. 3.

FIG. 5A is a cross-sectional view of a first embodiment of a foilsection of the hybrid foil bearing taken along line 5-5 of FIG. 3.

FIG. 5B is an exploded view of a second embodiment of a foil section ofthe hybrid foil bearing of FIG. 3.

FIG. 5C is a cross-sectional view of a third embodiment of a foilsection of the hybrid foil bearing taken along line 5-5 of FIG. 3.

FIG. 5D is a cross-sectional view of a fourth embodiment of a foilsection of the hybrid foil bearing taken along line 5-5 of FIG. 3.

FIG. 5E is a cross-sectional view of a fifth embodiment of a foilsection of the hybrid foil bearing taken along line 5-5 of FIG. 3.

FIG. 5F is a partially cut-away perspective view of a sixth embodimentof a foil section of the hybrid foil bearing of FIG. 3.

FIG. 6 is a cross-sectional view of a second embodiment of a hybrid foilbearing.

FIG. 7 is a cross-sectional view of a third embodiment of a hybrid foilbearing.

FIG. 8 is a cross-sectional view of a fourth embodiment of a hybrid foilbearing.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of air cycle machine 10, which includesfan section 12, compressor section 14, first turbine section 16, secondturbine section 18, tie rod 20, fan and compressor housing 22, sealplate 24, first turbine housing 26, and second turbine housing 28. Alsoshown in FIG. 1 is axis A.

Fan section 12, compressor section 14, first turbine section 16, andsecond turbine section 18 are all mounted on tie rod 20. Tie rod 20rotates about axis A. Fan and compressor housing 22 is connected to sealplate 24 and first turbine housing 26 with fasteners. Seal plate 24separates flow paths in fan and compressor housing 22 from flow paths infirst turbine housing 26. First turbine housing 26 is connected tosecond turbine housing 28 with fasteners. Fan and compressor housing 22,first turbine housing 26, and second turbine housing 28 together form anoverall housing for air cycle machine 10. Fan and compressor housing 22houses fan section 12 and compressor section 14, first turbine housing26 housing first turbine section 16, and second turbine housing 28houses second turbine section 18.

Fan section 12 includes fan inlet 30, fan duct 32, fan outlet 34, andfan rotor 36. Fan section 12 typically draws in ram air from a ram airscoop or alternatively from an associated gas turbine or other aircraftcomponent. Air is drawn into fan inlet 30 and is ducted through fan duct32 to fan outlet 34. Fan rotor 36 is positioned in fan duct 32 adjacentto fan inlet 30 and is mounted to and rotates with tie rod 20. Fan rotor36 draws air into fan section 12 to be routed through air cycle machine10.

Compressor section 14 includes compressor inlet 40, compressor duct 42,compressor outlet 44, compressor rotor 46, and diffuser 48. Air isrouted into compressor inlet 40 and is ducted through compressor duct 42to compressor outlet 44. Compressor rotor 46 and diffuser 48 arepositioned in compressor duct 42. Compressor rotor 46 is mounted to androtates with tie rod 20 to compress the air flowing through compressorduct 42. Diffuser 48 is a static structure through which the compressorair can flow after it has been compressed with compressor rotor 46. Airexiting diffuser 48 can then exit compressor duct 42 through compressoroutlet 44.

First turbine section 16 includes first turbine inlet 50, first turbineduct 52, first turbine outlet 54, and first turbine rotor 56. Air isrouted into first turbine inlet 50 and is ducted through first turbineduct 52 to first turbine outlet 54. First turbine rotor 56 is positionedin first turbine duct 52 and is mounted to and rotates with tie rod 20.First turbine rotor 56 will extract energy from the air passing throughfirst turbine section 16 to drive rotation of tie rod 20.

Second turbine section 18 includes second turbine inlet 60, secondturbine duct 62, second turbine outlet 64, and second turbine rotor 66.Air is routed into second turbine inlet 60 and is ducted through secondturbine duct 62 to second turbine outlet 64. Second turbine rotor 66 ispositioned in second turbine duct 62 and is mounted to and rotates withtie rod 20. Second turbine rotor 66 will extract energy from the airpassing through second turbine section 18 to drive rotation of tie rod20.

Air cycle machine 10 further includes first bearing 70, first rotatingshaft 72, second bearing 74, and second rotating shaft 76. First bearing70 is positioned in fan section 12 and is supported by fan andcompressor housing 22. First rotating shaft 72 extends between androtates with fan rotor 36 and compressor rotor 46. A radially outersurface of first rotating shaft 72 abuts a radially inner surface offirst bearing 70. Second bearing 74 is positioned in first turbinesection 16 and is supported by first turbine housing 26. Second rotatingshaft 76 extends between and rotates with first turbine rotor 56 andsecond turbine rotor 66. A radially outer surface of second rotatingshaft 76 abuts a radially inner surface of second bearing 74.

FIG. 2 is cross-sectional view of air compressor 100. Air compressor 100includes motor 102, compressor section 104, and tie rod 106. Also shownin FIG. 2 is axis B. Motor 102 drives compressor section 104 in aircompressor 100. Tie rod 106 extends through air compressor 100 and iscentered on axis B. Motor 102 and compressor section 104 are mounted totie rod 106. Motor 102 will drive tie rod 106 and cause it to rotate,which in turn will rotate compressor section 104.

Motor 102 includes motor housing 110, motor rotor 112, and motor stator114. Motor housing 110 surrounds motor rotor 112 and motor stator 114.Motor 102 is an electric motor with motor rotor 112 disposed withinmotor stator 114. Motor rotor 112 is rotatable about axis B. Motor rotor102 is mounted to tie rod 106 to drive rotation of tie rod 106 in aircompressor 100.

Compressor section 104 includes compressor housing 120, compressor inlet122, compressor outlet 124, and compressor rotor 126. Compressor housing120 includes a duct that forms compressor inlet 122 and a duct thatforms compressor outlet 124. Compressor inlet 122 draws air intocompressor section 104. Positioned in compressor housing 120 iscompressor rotor 126. Compressor rotor 126 is driven with motor 102 andis mounted on tie rod 106 to rotate with tie rod 106 about axis B. Airthat is drawn into compressor section 104 through compressor inlet 122is compressed with compressor rotor 126 before exiting compressorsection 104 through compressor outlet 124.

Air compressor 100 further includes first bearing 130, first rotatingshaft 132, second bearing 134, and second rotating shaft 136. Firstbearing 130 is positioned in motor 102 and is supported by motor housing110. First rotating shaft 132 is mounted on and rotates with tie rod106. A radially outer surface of first rotating shaft 132 abuts aradially inner surface of first bearing 130. Second bearing 134 ispositioned in motor 102 and is supported by motor housing 110. Secondrotating shaft 136 extends between and rotates with motor rotor 112 andcompressor rotor 126. A radially outer surface of second rotating shaft136 abuts a radially inner surface of second bearing 134.

FIGS. 3-8 describe various embodiments of a hybrid foil bearing. Any ofthe embodiments of the hybrid foil bearing can be used in air cyclemachine 10 shown in FIG. 1 and/or air compressor 100 shown in FIG. 2.Air cycle machine 10 shown in FIG. 1 and air compressor 100 shown inFIG. 2 are exemplary rotary machines and the hybrid foil bearing can beused in other rotary machines.

FIG. 3 is a cross-sectional view of a first embodiment of hybrid foilbearing 200. Hybrid foil bearing 200 includes first foil portion 210,metal mesh portion 212, second foil portion 214, bearing sleeve 220,first foil 222, metal mesh 224, second foil 226, and top foil 228. Alsoshown in FIG. 3 is axis Z.

Hybrid foil bearing 200 includes three sections, including first foilportion 210, metal mesh portion 212, and second foil portion 214. Metalmesh portion 212 is positioned between first foil portion 210 and secondfoil portion 214. Bearing sleeve 220 has a cylindrical shape and forms abody portion of hybrid foil bearing 200. As seen in FIG. 3, axis Zextends down a center of bearing sleeve 220. Bearing sleeve 220 has afirst wall thickness T₁ at first foil portion 210 and second foilportion 214, and a second wall thickness T₂ at metal mesh portion 212.First wall thickness T₁ is greater than second wall thickness T₂. Inalternate embodiments, bearing sleeve 220 could have the same thicknessacross the entire bearing sleeve 220.

First foil 222 is a cylindrical shape and is positioned in bearingsleeve 220 adjacent to an inner face of bearing sleeve 220 in first foilportion 210. Metal mesh 224 is a cylindrical shape and is positioned inbearing sleeve 220 adjacent to an inner face of bearing sleeve 220 inmetal mesh portion 212. Second foil 226 is a cylindrical shape and ispositioned in bearing sleeve 220 adjacent to an inner face of bearingsleeve 220 in second foil portion 214. Top foil 228 is a cylindricalshape and is positioned in bearing sleeve 220. Top foil 228 is adjacentto inner faces of first foil 222, metal mesh 224, and second foil 226.

FIG. 4 is a cross-sectional view of metal mesh section 212 of hybridfoil bearing 200 taken along line 4-4 of FIG. 3. Metal mesh section 212includes bearing sleeve 220, metal mesh 224, top foil 228, and airbearing gap 230. Also shown in FIG. 3 is shaft S.

Bearing sleeve 220 forms an outer body portion of metal mesh section 212of hybrid foil bearing 200. Positioned along an inner face of bearingsleeve 220 in metal mesh section 212 is metal mesh 224. Metal mesh 224includes a plurality of metal wires tangled together in a random manner.Metal mesh 224 can be made out of any suitable metal. Positioned alongan inner face of metal mesh 224 is top foil 228. A first end of top foil228 extends into metal mesh 224 to hold top foil 228 in position. In analternate embodiment, the first of top foil 228 extends through metalmesh 224 and into bearing sleeve 220. There is a gap between the firstend of top foil 228 and a second end of top foil 228 so that air canenter the space between shaft S and top foil 228. Shaft S is positionedadjacent to top foil 228 and extends through metal mesh section 212 ofhybrid foil bearing 200.

As shaft S rotates, air in hybrid foil bearing 200 will force top foil228 radially outwards, pushing top foil 228 further into metal mesh 224.This forms air bearing gap 230 between shaft S and top foil 228. Theutilization of metal mesh 224 in metal mesh portion 212 gives metal meshportion 212 good dampening characteristics, as metal mesh 224 has alarge number of surfaces contacting one another due to the plurality ofwires tangled together that are capable of absorbing the vibrations. Thegood damping characteristics of metal mesh section 212 reducesvibrations caused by shaft S rotating in hybrid foil bearing 200.

FIGS. 5A-5F show different embodiments of foil section 210 of hybridfoil bearing 200.

FIG. 5A is a cross-sectional view of a first embodiment of foil section210A of hybrid foil bearing 200 taken along line 5-5 of FIG. 3. Foilsection 210A includes bearing sleeve 220, bump foil 222A, top foil 228,and air bearing gap 230.

Bearing sleeve 220 forms an outer body portion of foil section 210A ofhybrid foil bearing 200. Positioned along an inner face of bearingsleeve 220 in foil section 210A is bump foil 222A. Bump foil 222Aincludes corrugations extending along the sheet. The corrugations can besized for stiffness and load capacity. Positioned along an inner face ofbump foil 222A is top foil 228. A first end of top foil 228 extendsradially outward and abuts bump foil 222A to hold top foil 228 in place.There is a gap between the first end of top foil 228 and a second end oftop foil 228 so that air can enter the space between shaft S and topfoil 228. Shaft S is positioned adjacent to top foil 228 and extendsthrough foil section 210A of hybrid foil bearing 200.

As shaft S rotates, air in hybrid foil bearing 200 will force top foil228 radially outwards, pushing top foil 228 further into bump foil 222Ato cause bump foil 222A to elastically deform. This forms air bearinggap 230 between shaft S and top foil 228. As seen in FIG. 5A, the numberof corrugations in bump foil 222A correlates to the number of contactpoints between top foil 228 and bump foil 222A. The utilization of bumpfoil 222A in foil portion 210A gives foil portion 210A high stiffnessand high load bearing capacity.

FIG. 5B is an exploded view of a second embodiment of foil section 210Bof hybrid foil bearing 200 of FIG. 3. Foil section 210B includes bearingsleeve 220, foil 222B, and top foil 228. Foil 222B includes first foilsection 240, second foil section 242, and third foil section 244.

Bearing sleeve 220 forms an outer body portion of foil section 210B ofhybrid foil bearing 200. Positioned along an inner face of bearingsleeve 220 in foil section 210B is bump foil 222A. Foil 222B is a bumpfoil with three different sections, including first foil section 240,second foil section 242, and third foil section 244. First foil section240, second foil section 242, and third foil section 244 are all bumpfoils with corrugations and they can have differently sizedcorrugations. In the embodiment shown in FIG. 5B, first foil section 240and third foil section 244 have corrugations of the same size. Inalternate embodiments, first foil section 240 and third foil section 244can have corrugations with different sizes. The corrugations can besized for stiffness and load capacity. Positioned along an inner face offoil 222B is top foil 228. There is a gap between a first end of topfoil 228 and a second end of top foil 228 so that air can enter thespace between shaft S and top foil 228. Shaft S is positioned adjacentto top foil 228 and extends through foil section 210B of hybrid foilbearing 200.

As shaft S rotates, air in hybrid foil bearing 200 will force top foil228 radially outwards, pushing top foil 228 further into foil 222B tocause foil 222B to elastically deform. This forms an air bearing gapbetween shaft S and top foil 228. As seen in FIG. 5B, the number ofcorrugations in each of first foil section 240, second foil section 242,and third foil section 244 of foil 222B correlates to the number ofcontact points between top foil 228 and foil 222B. The embodiment shownin FIG. 5B has larger corrugations in first foil section 240 and thirdfoil section 244 on either end of foil 222B. This gives first foilsection 240 and third foil section 244 a higher spring rate and top foil228 forms a greater seal against first foil section 240 and third foilsection 244. Second foil portion 242 has smaller corrugations and has alower spring rate. Air can be trapped in second foil portion 242 so thata higher air pressure is formed in second foil portion 242. This givesfoil 222B a higher load capacity. The utilization of foil 222B in foilportion 210B gives foil portion 210B high stiffness and high loadbearing capacity.

FIG. 5C is a cut-away cross-sectional view of a third embodiment of foilsection 210C of hybrid foil bearing 200 taken along line 5-5 of FIG. 3.Foil section 210C includes bearing sleeve 220, foil 222C₁, foil 222C₂,top foil 228, and air bearing gap 230.

Bearing sleeve 220 forms an outer body portion of foil section 210C ofhybrid foil bearing 200. Positioned along an inner face of bearingsleeve 220 in foil section 210C are foil 222C₁ and foil 222C₂. Foil222C₁ and foil 222C₂ are bump foils. Foil 222C₁ is adjacent to the innerface of bearing sleeve 220 and foil 222C₂ is adjacent to the inner faceof foil 222C₁. In the embodiment shown in FIG. 5C, foil 222C₁ hassmaller corrugations and foil 222C₂ has larger corrugations. Inalternate embodiments, foil 222C₁ has corrugations that are larger thanthe size of the corrugations of foil 222C₂. Positioned along an innerface of foil 222C₂ is top foil 228. A first end of top foil 228 extendsradially outward and abuts foil 222 C2 to hold top foil 228 in place.There is a gap between the first end of top foil 228 and a second end oftop foil 228 so that air can enter the space between shaft S and topfoil 228. Shaft S is positioned adjacent to top foil 228 and extendsthrough foil section 210C of hybrid foil bearing 200.

As shaft S rotates, air in hybrid foil bearing 200 will force top foil228 radially outwards, pushing top foil 228 further into foil 222C₂ tocause foil 222C₂ to elastically deform. This forms air bearing gap 230between shaft S and top foil 228. As seen in FIG. 5C, the number ofcorrugations in bump foil 222C₂ correlates to the number of contactpoints between top foil 228 and foil 222C₂. Further, there are contactpoints between foil 222C₂ and foil 222C₁. Having contact points betweentop foil 228 and foil 222C₂ and between foil 222C₂ and foil 222C₁increases the load capacity of foil 222C₁ and foil 222C₂. Theutilization of foil 222C₁ and foil 222C₂ in foil portion 210C gives foilportion 210C high stiffness and high load bearing capacity.

FIG. 5D is a cross-sectional view of a fourth embodiment of foil section210D of hybrid foil bearing 200 taken along line 5-5 of FIG. 3. Foilsection 210D includes bearing sleeve 220, plurality of leaf foils 222D,air bearing gap 230, and plurality of notches 246.

Bearing sleeve 220 forms an outer body portion of foil section 210D ofhybrid foil bearing 200. Positioned along an inner face of bearingsleeve 220 in foil section 210D are plurality of leaf foils 222D andplurality of notches 246. Bearing sleeve 220 has plurality of notches246 cut into it on an inner diameter of bearing sleeve 220. A first endof each leaf foil 222D is positioned in one of notches 246 in bearingsleeve 220. Each leaf foil 222D extends outward from one notch 246 andruns along an inner diameter of bearing sleeve 220. A second end of eachleaf foil 222D overlaps an adjacent leaf foil 222D. In the embodimentshown in FIG. 5D, foil section 210D includes nine leaf foils 222D, butfoil section 210D can include any number of leaf foils 222D in alternateembodiments. Shaft S is positioned adjacent to plurality of leaf foils222D and extends through foil section 210D of hybrid foil bearing 200.

Foil section 210D does not include a top foil, as plurality of leaffoils 222D extend around the entire inner diameter of bearing sleeve 220and act as the top foil that abuts shaft S. When foil section 210D isused in hybrid foil bearing 200 shown in FIG. 3, top foil 228 will notextend across foil section 210D. As shaft S rotates, air in hybrid foilbearing 200 will force plurality of leaf foils 222D radially outwards,causing plurality of leaf foils 222D to elastically deform. This formsair bearing gap 230 between shaft S and plurality of leaf foils 222D.The utilization of plurality of leaf foils 222D in foil portion 210Dgives foil portion 210D high stiffness and high load bearing capacity.

FIG. 5E is a cross-sectional view of a fifth embodiment of foil section210E of hybrid foil bearing 200 taken along line 5-5 of FIG. 3. Foilsection 210E includes bearing sleeve 220, plurality of foils 222E, topfoil 228, air bearing gap 230, and plurality of supports 248.

Bearing sleeve 220 forms an outer body portion of foil section 210E ofhybrid foil bearing 200. Positioned along an inner face of bearingsleeve 220 in foil section 210E are plurality of foils 222E andplurality of supports 248. There are three supports 248 in theembodiment shown in FIG. 5E, but there can be any number of supports 248in alternate embodiments. Plurality of supports 248 extend into bearingsleeve 220 and form three distinct regions along an inner diameter ofbearing sleeve 220. Plurality of foils 222E are positioned betweenplurality of supports 248. Plurality of foils 222E are foil strips.Plurality of foils 222E are arranged to form cantilevers C. In theembodiment shown in FIG. 5E, there are three cantilevers C formed ineach region defined by plurality of supports 248. In an alternateembodiment, any number of cantilevers C can be formed. Positioned alongan inner face of plurality of foils 222E is top foil 228. Top foil 228abuts each support 248 in foil section 210E. Shaft S is positionedadjacent to top foil 228 and extends through foil section 210E of hybridfoil bearing 200.

As shaft S rotates, air in hybrid foil bearing 200 will force top foil228 radially outwards, pushing top foil 228 further into plurality offoils 222E to cause plurality of foils 222E to elastically deform. Thisforms air bearing gap 230 between shaft S and top foil 228. CantileversC formed with plurality of foils 222E absorb stress from the deformationof plurality of foils 222E while helping plurality of foils 222E retaintheir strength. The utilization of plurality of foils 222E formingcantilevers C in foil portion 210E gives foil portion 210E highstiffness and high load bearing capacity.

FIG. 5F is a partially cut-away perspective view of a sixth embodimentof foil section 210F of hybrid foil bearing 200 of FIG. 3. Foil section210F includes bearing sleeve 220, plurality of foils 222F, plurality oftop foils 228, air bearing gap 230, and plurality of projections 249.

Bearing sleeve 220 forms an outer body portion of foil section 210F ofhybrid foil bearing 200. Positioned along an inner face of bearingsleeve 220 in foil section 210F are plurality of foils 222F andplurality of projections 249. Plurality of projections 249 extendradially inwards from bearing sleeve 220 and a lip is formed on eitherside of each projection 249. There are three projections 249 in theembodiment shown in FIG. 5F, but there can be any number of projections249 in alternate embodiments. Plurality of projections 249 form threedistinct regions along an inner diameter of bearing sleeve 220.Plurality of foils 222F are positioned between plurality of projections249. Plurality of foils 222F are spring foils. Each foil 222F includescorrugations along extending along the sheet. The corrugations can besized for strength and stiffness. One foil 222F is positioned in eachregion formed between plurality of projections 249. Positioned along aninner face of plurality of foils 222F are plurality of top foils 228.There are three top foils 228 in the embodiment shown in FIG. 5F, butthere can be any number of top foils 228 to correspond to the number offoils 222F in alternate embodiments. A first end of each top foil 228 isretained with a lip of a first projection 249 and a second end of eachtop foil 228 is retained with a lip of a second projection 249. Shaft Sis positioned adjacent to plurality of top foils 228 and extends throughfoil section 210F of hybrid foil bearing 200.

As shaft S rotates, air in hybrid foil bearing 200 will force pluralityof top foils 228 radially outwards, pushing plurality of top foils 228further into plurality of foils 222F to cause plurality of foils 222F toelastically deform. This forms air bearing gap 230 between shaft S andplurality of top foils 228. As seen in FIG. 5F, the number ofcorrugations in plurality of foils 222F correlates to the number ofcontact points between plurality of top foils 228 and plurality of foils222F. The utilization of plurality of foils 222F in foil portion 210Fgives foil portion 210F high stiffness and high load bearing capacity.

FIGS. 5A-5F are described with reference to foil section 210 of hybridfoil bearing 200, however foil section 214 of hybrid foil bearing 200can have any of the structures shown in FIGS. 5A-5F. Foil section 210and foil section 214 can have the same structure or different structuresin different embodiments.

FIGS. 3-5F show hybrid foil bearing 200 with foil section 210, metalmesh section 212, and foil section 214. Hybrid foil bearing 200 utilizesthe high stiffness and high load bearing capacity of foil section 210and foil section 214, while also utilizing the good dampingcharacteristics of metal mesh section 212. Bearings that utilize only afoil section face issues with sub-synchronous whirl, which is caused bythe uncontrolled vibration of the shaft extending through the bearing.The uncontrolled vibrations occur because bump foils do not have gooddampening characteristics. Bearings that utilize only a metal meshsection faces issues with sag and creep over time, causing the shaftextending through the bearing to become off centered. When a shaftbecomes off centered, any components that are rotating with the shaftwill become off centered and can cause these parts to rub againststationary parts. Rubbing these parts against stationary parts can causeboth parts to wear, requiring that the parts be replaced more often andposing a risk that the parts will fail.

Hybrid foil bearing 200 utilizes first foil section 210, metal meshsection 212, and second foil section 214. First foil section 210 andsecond foil section 214 have high stiffness and high load bearingcapabilities. Metal mesh section 212 has good dampening characteristics.Utilizing first foil section 210, metal mesh section 212, and secondfoil section 214 creates hybrid foil bearing 200 that has high stiffnessand high load bearing capabilities while also having good dampeningcharacteristics.

FIG. 6 is a cross-sectional view of a second embodiment of hybrid foilbearing 250. Hybrid foil bearing 250 includes first metal mesh portion260, foil portion 262, second metal mesh portion 264, bearing sleeve270, first metal mesh 272, foil 274, second metal mesh 276, and top foil278. Also shown in FIG. 6 is axis Z.

Hybrid foil bearing 250 includes three sections, including first metalmesh portion 260, foil portion 262, and second metal mesh portion 264.Foil portion 262 is positioned between first metal mesh portion 260 andsecond metal mesh portion 264. Bearing sleeve 270 has a cylindricalshape and forms a body portion of hybrid foil bearing 250. As seen inFIG. 6, axis Z extends down a center of bearing sleeve 270. Bearingsleeve 270 has a first wall thickness T₁ at first metal mesh portion 260and second metal mesh portion 264, and a second wall thickness T₂ atfoil portion 262. First wall thickness T₁ is less than second wallthickness T₂. In alternate embodiments, bearing sleeve 270 has the samethickness across bearing sleeve 270.

First metal mesh 272 is a cylindrical shape and is positioned in bearingsleeve 270 adjacent to an inner face of bearing sleeve 270 in firstmetal mesh portion 260. Foil 274 is a cylindrical shape and ispositioned in bearing sleeve 270 adjacent to an inner face of bearingsleeve 270 in foil portion 262. Second metal mesh 276 is a cylindricalshape and is positioned in bearing sleeve 270 adjacent to an inner faceof bearing sleeve 270 in second metal mesh portion 264. Top foil 278 isa cylindrical shape and is positioned in bearing sleeve 270. Top foil278 is adjacent to inner faces of first metal mesh 272, foil 274, andsecond metal mesh 276.

FIG. 7 is a cross-sectional view of a third embodiment of hybrid foilbearing 300. Hybrid foil bearing 300 includes first metal mesh portion310, first foil portion 312, second foil portion 314, second metal meshportion 316, bearing sleeve 320, first metal mesh 322, first foil 324,second foil 326, second metal mesh 328, and top foil 330. Also shown inFIG. 7 is axis Z.

Hybrid foil bearing 300 includes four sections, including first metalmesh portion 310, first foil portion 312, second foil portion 314, andsecond metal mesh portion 316. First foil portion 312 is positionedbetween first metal mesh portion 310 and second foil portion 314. Secondfoil portion 314 is positioned between first foil portion 312 and secondmetal mesh portion 316. Bearing sleeve 320 has a cylindrical shape andforms a body portion of hybrid foil bearing 300. As seen in FIG. 7, axisZ extends down a center of bearing sleeve 320. Bearing sleeve 320 has afirst wall thickness T₁ at first metal mesh portion 310 and second metalmesh portion 316, and a second wall thickness T₂ at first foil portion312 and second foil portion 314. First wall thickness T₁ is less thansecond wall thickness T₂.

First metal mesh 322 is a cylindrical shape and is positioned in bearingsleeve 320 adjacent to an inner face of bearing sleeve 320 in firstmetal mesh section 310. First foil 324 is a cylindrical shape and ispositioned in bearing sleeve 320 adjacent to an inner face of bearingsleeve 320 in first foil portion 312. Second foil 326 is a cylindricalshape and is positioned in bearing sleeve 320 adjacent to an inner faceof bearing sleeve 320 in second foil portion 314. Second metal mesh 328if a cylindrical shape and is positioned in bearing sleeve 320 adjacentto an inner face of bearing sleeve 320 in second metal mesh portion 316.Top foil 330 is a cylindrical shape and is positioned in bearing sleeve320. Top foil 330 is adjacent to inner faces of first metal mesh 322,first foil 324, second foil 326, and second metal mesh 328.

FIG. 8 is a cross-sectional view of a fourth embodiment of hybrid foilbearing 350. Hybrid foil bearing 350 includes metal mesh portion 360,foil portion 362, bearing sleeve 370, metal mesh 372, foil 374, and topfoil 376. Also shown in FIG. 8 is axis Z.

Hybrid foil bearing 350 includes two sections, including metal meshportion 360 and foil portion 362. Metal mesh portion 360 is positionedadjacent to foil portion 362. Bearing sleeve 370 has a cylindrical shapeand forms a body portion of hybrid foil bearing 350. As seen in FIG. 8,axis Z extends down a center of bearing sleeve 370. Bearing sleeve 370has a first wall thickness T₁ at metal mesh portion 360 and a secondwall thickness T₂ at foil portion 362. First wall thickness T₁ is lessthan second wall thickness T₂. In an alternate embodiment, bearingsleeve 370 has the same thickness across bearing sleeve 370.

Metal mesh 372 is a cylindrical shape and is positioned in bearingsleeve 370 adjacent to an inner face of bearing sleeve 370 in metal meshportion 360. Foil 374 is a cylindrical shape and is positioned inbearing sleeve 370 adjacent to an inner face of bearing sleeve 370 infoil portion 362. Top foil 376 is a cylindrical shape and is positionedin bearing sleeve 370. Top foil 376 is adjacent to inner faces of metalmesh 372 and foil 374.

Hybrid foil bearing 200 shown in FIG. 3, hybrid foil bearing 250 shownin FIG. 6, hybrid foil bearing 300 shown in FIG. 7, and hybrid foilbearing 350 shown in FIG. 8 are all variations of a hybrid foil bearing.Further variations are appreciated and a hybrid foil bearing can includeany number of metal mesh portions combined with any number of foilportions with varying arrangements. Air cycle machine 10 shown in FIG. 1and air compressor 100 shown in FIG. 2 are exemplary rotary machines inwhich a hybrid foil bearing can be used. Air cycle machine 10 shown inFIG. 1 includes first bearing 70 and second bearing 74 that can behybrid foil bearings. Air compressor 100 shown in FIG. 2 includes firstbearing 130 and second bearing 134 that can be hybrid foil bearings. Anyof hybrid foil bearing 200 shown in FIG. 3, hybrid foil bearing 250shown in FIG. 6, hybrid foil bearing 300 shown in FIG. 7, and hybridfoil bearing 350 shown in FIG. 8 or variations thereof can be used asfirst bearing 70 and/or second bearing 74 in air cycle machine 10 shownin FIG. 1 and/or first bearing 130 and/or second bearing 134 in aircompressor 100 shown in FIG. 2.

DISCUSSION OF POSSIBLE EMBODIMENTS

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

A bearing includes a bearing sleeve with a first portion and a secondportion adjacent to the first portion. A bump foil extends along aninner face of the first portion of the bearing sleeve and a metal meshextends along an inner face of the second portion of the bearing sleeve.A top foil extends along an inner face of the bump foil of the firstportion and the metal mesh of the second portion.

The bearing of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

The bearing can include a third portion in the bearing sleeve adjacentto the second portion, and a bump foil extending along an inner face ofthe third portion of the bearing sleeve, wherein the top foil extendsalong an inner face of the bump foil of the third portion.

The bearing sleeve has a first wall thickness at the first portion andthe third portion that is greater than a second wall thickness at thesecond portion.

The bearing can include a third portion in the bearing sleeve adjacentto the first portion, and a metal mesh extending along an inner face ofthe third portion of the bearing sleeve, wherein the top foil extendsalong an inner face of the metal mesh of the third portion.

The bearing sleeve has a first wall thickness at the first portion andthe third portion that is lesser than a second wall thickness at thesecond portion.

The bump foil has a first section having corrugations with a first sizeand a second section having corrugations with a second size, wherein thefirst size is larger than the second size.

The bump foil is a first bump foil and the bearing further includes asecond bump foil extending along an inner face of the first bump foil,wherein the first bump foil and the second bump foil have differentsized corrugations.

A rotary machine includes a shaft that is configured to rotate in therotary machine, a stationary component positioned outward from theshaft, and a hybrid foil bearing positioned between the shaft and thestationary component. The hybrid foil bearing has a first bump foilportion and a first metal mesh portion adjacent to the first bump foilportion.

The rotary machine of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

The hybrid foil bearing further includes a bearing sleeve with the firstbump foil portion and the first metal mesh portion, a first bump foilpositioned in the first bump foil portion of the bearing sleeve, a firstmetal mesh positioned in the first metal mesh portion of the bearingsleeve, and a top foil extending along an inner face of the first bumpfoil in the first bump foil portion and the first metal mesh in thefirst metal mesh portion.

The hybrid foil bearing further includes a second bump foil portion inthe bearing sleeve adjacent to the first metal mesh portion, and asecond bump foil extending along an inner face of the second bump foilportion of the bearing sleeve, wherein the top foil extends along aninner face of the second bump foil of the second bump foil portion.

The hybrid foil bearing further includes a second metal mesh portion inthe bearing sleeve adjacent to the first bump foil portion, and a secondmetal mesh extending along an inner face of the second metal meshportion of the bearing sleeve, wherein the top foil extends along aninner face of the second metal mesh of the second metal mesh portion.

The first bump foil has a first section having corrugations with a firstsize and a second section having corrugations with a second size,wherein the first size is larger than the second size.

The hybrid foil bearing further includes a second bump foil extendingalong an inner face of the first bump foil, wherein the first bump foiland the second bump foil have different sized corrugations.

The rotary machine can include a tie rod extending along a central axisof the rotary machine, wherein the shaft is configured to rotate withthe tie rod; compressor section including a compressor inlet, acompressor outlet, and a compressor rotor, wherein the compressor rotoris configured to rotate with the tie rod; and a motor including a motorhousing, a motor stator, and a motor rotor.

The rotary machine can include a tie rod extending along a central axisof the rotary machine, wherein the shaft is configured to rotate withthe tie rod; a fan section with a fan inlet, a fan outlet, and a fanrotor, wherein the fan rotor is configured to rotate with the tie rod; acompressor section including a compressor inlet, a compressor outlet,and a compressor rotor, wherein the compressor rotor is configured torotate with the tie rod; a first turbine section including a firstturbine inlet, a first turbine outlet, and a first turbine rotor,wherein the first turbine rotor is configured to rotate with the tierod; and a second turbine section including a second turbine inlet, asecond turbine outlet, and a second turbine rotor, wherein the secondturbine rotor is configured to rotate with the tie rod.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

The invention claimed is:
 1. A bearing comprising: a bearing sleeve witha first portion and a second portion adjacent to the first portion; abump foil extending along an inner face of the first portion of thebearing sleeve; a metal mesh extending along an inner face of the secondportion of the bearing sleeve; and a top foil extending along an innerface of the bump foil of the first portion and the metal mesh of thesecond portion.
 2. The bearing of claim 1, and further comprising: athird portion in the bearing sleeve adjacent to the second portion; anda bump foil extending along an inner face of the third portion of thebearing sleeve; wherein the top foil extends along an inner face of thebump foil of the third portion.
 3. The bearing of claim 2, wherein thebearing sleeve has a first wall thickness at the first portion and thethird portion that is greater than a second wall thickness at the secondportion.
 4. The bearing of claim 1, and further comprising: a thirdportion in the bearing sleeve adjacent to the first portion; and a metalmesh extending along an inner face of the third portion of the bearingsleeve; wherein the top foil extends along an inner face of the metalmesh of the third portion.
 5. The bearing of claim 4, wherein thebearing sleeve has a first wall thickness at the first portion and thethird portion that is lesser than a second wall thickness at the secondportion.
 6. The bearing of claim 1, wherein the bump foil has a firstsection having corrugations with a first size and a second sectionhaving corrugations with a second size, wherein the first size is largerthan the second size.
 7. The bearing of claim 1, wherein the bump foilis a first bump foil and further comprising: a second bump foilextending along an inner face of the first bump foil, wherein the firstbump foil and the second bump foil have different sized corrugations. 8.A rotary machine comprising: a shaft that is configured to rotate in therotary machine; a stationary component positioned outward from theshaft; and a hybrid foil bearing positioned between the shaft and thestationary component, wherein the hybrid foil bearing has a first bumpfoil portion and a first metal mesh portion adjacent to the first bumpfoil portion.
 9. The rotary machine of claim 8, wherein the hybrid foilbearing further comprises: a bearing sleeve with the first bump foilportion and the first metal mesh portion; a first bump foil positionedin the first bump foil portion of the bearing sleeve; a first metal meshpositioned in the first metal mesh portion of the bearing sleeve; and atop foil extending along an inner face of the first bump foil in thefirst bump foil portion and the first metal mesh in the first metal meshportion.
 10. The rotary machine of claim 9, wherein the hybrid foilbearing further comprises: a second bump foil portion in the bearingsleeve adjacent to the first metal mesh portion; and a second bump foilextending along an inner face of the second bump foil portion of thebearing sleeve; wherein the top foil extends along an inner face of thesecond bump foil of the second bump foil portion.
 11. The rotary machineof claim 9, wherein the hybrid foil bearing further comprises: a secondmetal mesh portion in the bearing sleeve adjacent to the first bump foilportion; and a second metal mesh extending along an inner face of thesecond metal mesh portion of the bearing sleeve; wherein the top foilextends along an inner face of the second metal mesh of the second metalmesh portion.
 12. The rotary machine of claim 9, wherein the first bumpfoil has a first section having corrugations with a first size and asecond section having corrugations with a second size, wherein the firstsize is larger than the second size.
 13. The rotary machine of claim 9,wherein the hybrid foil bearing further comprises: a second bump foilextending along an inner face of the first bump foil, wherein the firstbump foil and the second bump foil have different sized corrugations.14. The rotary machine of claim 8, and further comprising: a tie rodextending along a central axis of the rotary machine, wherein the shaftis configured to rotate with the tie rod; a compressor section includinga compressor inlet, a compressor outlet, and a compressor rotor, whereinthe compressor rotor is configured to rotate with the tie rod; and amotor including a motor housing, a motor stator, and a motor rotor. 15.The rotary machine of claim 8, and further comprising: a tie rodextending along a central axis of the rotary machine, wherein the shaftis configured to rotate with the tie rod; a fan section with a faninlet, a fan outlet, and a fan rotor, wherein the fan rotor isconfigured to rotate with the tie rod; a compressor section including acompressor inlet, a compressor outlet, and a compressor rotor, whereinthe compressor rotor is configured to rotate with the tie rod; a firstturbine section including a first turbine inlet, a first turbine outlet,and a first turbine rotor, wherein the first turbine rotor is configuredto rotate with the tie rod; and a second turbine section including asecond turbine inlet, a second turbine outlet, and a second turbinerotor, wherein the second turbine rotor is configured to rotate with thetie rod.